It is well known to utilize an earth drilling bit having a body with a threaded pin on its upper end for connection to a drilling string for drilling oil and/or gas wells. One type of drilling bit, such as shown in U.S. Pat. No. 4,558,753, utilizes a plurality of cutting elements having a stud formed of one material, mounted onto and projecting from the bit cutting face, and carrying a bonded polycrystalline diamond cutting tool (PDC) for engaging the earth to be bored. Such cutting elements are generally flat or concave. However, as the drill bit is used, wear occurs to the relatively sharp cutting edges of the cutter which consequentially results in flat surfaces. The total flat area of the cutters contacting the formation increases as rotation continues, generating undesirable excessive heat and torque that prematurely shortens the bit effectiveness and life.
Because the earth formation includes different strata some of which are extremely hard and some of which are relatively soft, it has been difficult to design a cutting element that will drill efficiently through stratified formations while at the same time reducing damage and wear to the cutting elements. Various solutions that have been proposed are staggering the heights of the cutting elements, varying the side and back rake of the cutting faces, providing concave cutting faces to provide various values of back rake angles. However, in all of these proposed solutions, the tips of the cutting elements wear flat and generate non-productive friction that dramatically shortens the drill bit life. Furthermore, while fluid circulation systems are employed in PDC bits for circulating drilling fluid through the bit for bottom hole cleaning, cooling the cutter elements and transporting the cuttings from beneath the bit to the well annulus for circulation out of the hole, such systems do not optimize the effectiveness of the circulation system.